April 2007, 28(2) 427-432 (2007) For personal use only Commercial distribution of this copy is illegal
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Harvesting impact on herbaceous understory, forest floor and top soil properties on skid road in a beech (Fagus orientalis Lipsky) stand Murat Demir*1, E. Makineci2 and E. Yilmaz3 1
Department of Forest Construction and Transportation, Faculty of Forestry, Istanbul University, Bahcekoy, Sariyer-34473, Istanbul, Turkey 2 Department of Soil Science and Ecology, Faculty of Forestry, Istanbul University, Bahcekoy, Sariyer-34473, Istanbul, Turkey 3 Department of Forest Yield and Biometry, Faculty of Forestry, Istanbul University, Bahcekoy, Sariyer-34473, Istanbul, Turkey (Received: August 10, 2005 ; Revised received: November 28, 2005 ; Accepted: December 30, 2005) Abstract: In this study, the impact of production work on the skid roads that have been carried out for many years by manpower, animal power or machinery in a beech (Fagus orientalis Lipsky) stand have been examined. For this purpose, herbaceous understory, forest floor and soil samples were collected from the undisturbed area and the skid road. Weight per unit area (kg ha-1), organic matter ratio and moisture of forest floor and herbaceous understory were measured in undisturbed area and the skid road. Soil characteristics were examined at two different depths (0-5 cm and 5-10 cm). Percentages of sand, silt and clay, electrical conductivity, weight of fine soil (2mm), root mass, organic carbon, moisture equivalent, total porosity, bulk density, moisture, compaction and pH values in the soil were determined. It has been determined that the amount of herbaceous understory and forest floor on the skid road decreased considerably compared to those of the undisturbed area. Parallel to this, the amount of organic matter in the herbaceous understory and the forest floor on the skid road decreased as well. It has been concluded that there are crucial differences between the values of compaction, bulk density, fine soil weight, total porosity and moisture equivalent of the soil samples collected from both the skid road and the undisturbed area at both depth levels, as a result of compaction of the soil caused by harvesting works. Key words: Harvesting impact, Skidding, Soil, Forest floor, Herbaceous understory
Introduction Production work being carried out in the forest have many negative impact on the forest ecosystem is well known. It has also been determined that the production and skidding negatively affect the amount and variety of forest floor and herbaceous understory as well as youth development and living conditions of the soil organisms (Arocena, 2000; Bengtsson et al., 1998; Buckley et al., 2003; Gilliam, 2002; Godefroid and Koedam, 2004; Johnston and Johnston, 2004; Marshall, 2000; Messina et al., 1997; Wang, 1997; Williamson and Neilsen, 2003). Skidding or yarding on terrain requires the construction of relatively dense network of forest roads including skid roads, haul roads and landings (Ketcheson et al., 1999; Swift, 1988). Logging operations can cause significant and wide spread soil disturbance, including removal, mixing and compaction of the various soil layers. Timber harvesting can adversely affect both soil physical properties and soil nutrient levels. Logging can cause diminished growth of subsequent tree rotations, significant increase in runoff and sediment loads (Laffan et al., 2001). Erosion of organic and nutrient rich surface soil and compaction decrease forest productivity (Pritchett and Fisher, 1987) and the transport of sediment to streams and subsequent sedimentation leads to loss of stream habitat and altered stream hydrology. The soil micro flora and fauna complement each other in the comminution of litter, mineralization of essential plant nutrients and conservation of these nutrients within the soil system. Harvesting directly affects
these processes through the reduction and redistribution of organic matter, compaction, changes in plant cover, and modification of microclimate (Marshall, 2000). The extent of severe disturbance from ground based timber harvesting systems varies due to slope and terrain, timber harvesting machines, methods of designating skid roads and harvesting season. Ground based skidding may result in soil compaction and other soil structural changes, influencing soil water retention, and reducing soil aeration, drainage and root penetration (Froehlich et al., 1986). Soil damage on forest roads, skid roads and landings includes the removal of the organic layer and topsoil, soil compaction and erosion of the exposed soil. The soil damage affects hill slope infiltration and surface and subsurface flows (Binkley, 1986). In this study, the impact on the herbaceous understory, forest floor and soil properties in a beech stand (Fagus orientalis Lipsky) caused by production work on the skid roads have been researched. Materials and Methods Research area is in the boundaries of zone 82 of Istanbul Belgrad forest. Belgrad forest covering a surface area of 5441.71 ha is located in the Marmara geographical region between latitudes 41 o09'-41 o12'N and longitudes 28 o54'29 o00'E (Fig. 1).
*Corresponding author: E-Mail:
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April, 2007
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Demir et al.
THE LOCATION OF ISTANBUL BELGRAD FOREST IN TURKEY
BLACK SEA
Kilyos
Sariyer BELGRAD FOREST
Beykoz Istinye
Rumelihisari
Anadoluhisari
Ortakoy
26ºE
45ºE RUSSIA
BULGARIA
Uskudar
ISTANBUL
Bakirkoy
42ºN
Kadikoy
Yesilkoy
BLACK SEA
42ºN GEORGIA ARMENIA AZERBAIJAN
GREECE
TURKEY MARMARA SEA
N
IRAN
AEGEAN SEA
36ºN
36ºN SYRIA
IRAQ
MEDITERREAN SEA
Research Area 0
4
2
6 km
0
250
500 km
26ºE
45ºE
Fig. 1: The location of Istanbul Belgrad Forest in Turkey
According to the data given by Bahcekoy meteorology station, average annual precipitation is 1074.4 mm, average annual temperature is 12.8oC, average high temperature is17.8oC and the average low temperature is 9oC. The climate of Istanbul Belgrad Forest is close to sea (ocean) climate with medium water deficit in summers. Vegetation period maintains for 7.5 months (230 days) in average. The period of study is September 2004 and research area is oriental beech (Fagus orientalis Lipsky) stand having canopy cover as 0.8, average diameter as 23.12 cm, average height as 24.14 m and stand density as 1400 trees/ha. Average altitude of the research area is 140 m, slope is 10-15% with SW aspect. Dominant herbaceous vegetation species on the undisturbed area and skid road are Hedera helix L., Ruscus aculeatus L., Ruscus hypoglossum L., Rubus sp., Viola sp., Galium odoratum (L.) Scop., Salvia forskahle L. and Trachystemon orientale (L.) G.Don. The skidding road passing through the stand in West-East direction has long been used (since 1956) to skid the logs out of the area. It was estimated that 135 m³ timbers was skidded annually in harvest activities on the skid road. The harvested timbers are also being towed by tractors with a rope along with skidding by means of manpower and animals. To examine the impact of skidding on the skid road, the forest floor, herbaceous understory and the upper soil layer (down to 10 cm depth) in
Journal of Environmental Biology
April, 2007
comparison with the undisturbed stand, the skid road was sampled at 7 different points at 10 m intervals (7 samples were taken from each of herbaceous understory, forest floor, 0-5 cm soil and 5-10 cm soil). Soil samples from 7 different points were taken again at 10 m intervals (from each of the herbaceous understory, forest floor, 0-5 cm soil and 5-10 cm soil) from the undisturbed area protected from skidding at least 25-30 m away from the skid road (at least one tree length away to ensure prevention of side impact). Herbaceous understory samples were taken by cutting above ground parts of all herbaceous understory in 1 m2 area and the samples of the forest floor were taken from 0.25 m2 area by collecting all the forest floor in that area. Soil compaction at the places where herbaceous understory and forest floor samples were taken was measured at 0-5 cm and 5-10 cm depths by using a pocket penetrometer. Soil samples were taken from 0-5 cm and 5-10 cm with the aid of 100 cm3 steel soil cylinders. A total of 300 cm3 soil sample was taken for each of the sampling points. All samples were collected in September 2004. All samples were put in polyethylene bags and labeled. Samples brought to the laboratory from the research area were promptly weighed (within one hour) and percentage of moisture and weight of oven dried samples were calculated from the difference between the values of wet and oven dried samples after making the herbaceous understory samples dried under 65oC and forest floor and soil samples dried under 105oC for
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twenty four hour in an oven. Organic matter amount were found by loss on ignition method after grinding and burning under 550oC the herbaceous understory and forest floor samples. Soil samples were sieved through 2 mm sieves and thus, fine soil (2mm) weights were found.Texture (by Bouyoucos hydrometer method), organic carbon (by Walkley and Black wet digestion method), bulk density, total porosity, moisture equivalent, pH and electrical conductivity values were measured in the laboratory (Karaoz, 1989a, 1989b, 1992).
the organic matter content and herbaceous understory amounts, the organic matter amount in unit area (kg ha-1) was higher in the undisturbed area (669.81 kg ha-1) (Table 1). The reason why the skid road had a higher content of organic matter is more likely because of the different herbaceous species on the skid road and in the undisturbed area. Many similar researches have set the negative impact of skidding on the herbaceous understory (Buckley et al., 2003; Gilliam, 2002; Godefroid and Koedam, 2004; Johnston and Johnston, 2004; Nugent et al., 2003).
The mean organic matter content in the undisturbed area (85.63%) was considerably higher than that of the skid road (81.42%) (Table 1). Subject to the notable differences between
Properties of forest floor: Mean forest floor weight in unit area has been found considerably higher in the undisturbed area (13577.30 kg ha-1) than the skid road (7935.86 kg ha-1) (Table 2). Less forest floor on the skid roads shows that the forest floor has decreased because of carrying caused by skidding. In addition, some of the trees along the skidding route were cut during opening of the skid roads to ensure easy transportation and skidding of the harvested timbers. This might have result in less populated trees along the skid roads compared to the undisturbed area. Subject to less dense stand, decreasing of the falling forest floor may be another factor of the decreasing forest floor on the skid road. Average organic matter content of the forest floor along the skid road (61.03%) has been found less than that of the undisturbed area (71.25%); however, statistically this difference was not significant (Table 2). The forest floor mean organic matter amount (9985.86 kg ha-1) in the unit area of the undisturbed area was seriously higher subject to the differences in the total forest floor weight (Table 2). While the average forest floor moisture content in the undisturbed area was 37.27%, the moisture content on the skid road was 25.20% (Table 2). The forest floor in the undisturbed area had considerably higher moisture content than the skid road. The reason why the forest floor along the skid road had less moisture content must be, more likely, because of less stand density and subject to the decreasing herbaceous understory, increase in evaporation because of being exposed to more intense sunlight as a result of the decreasing skid road cover. Moreover, likely impacts of skidding on the forest floor structure might be an effective factor on the forest floor moisture along with the decreasing forest floor. Impacts of skidding and production works on the forest floor give similar results in many researches (Arocena, 2000; Ballard, 2000; Bengtsson et al., 1998; Jacobson et al., 2000; Johnston and Johnston, 2004, Marshall, 2000; Rab, 2004).
Table - 1: Some properties of herbaceous understory
Table - 2: Some properties of forest floor
The values for the undisturbed area and the skid road p
